1. Field of the Invention
The invention relates generally to the field of communication networks. More particularly, the invention relates to the use of splitter-combiners in ring communication networks.
2. Discussion of the Related Art
Communication nodes are designed and used for point to point communications over a network. A communications node is a transmitting and receiving (TX/RX) source.
Stringing a plurality of nodes together into a ring network is well known to those skilled in the art of communications. What is also well known is that an interruption in communication service can be both inconvenient and costly.
For instance, a conventional ring network is shown in FIG. 1, where a physical bus logical ring is depicted with three nodes 110, 120, 130 communicatively coupled to a headend. Each of the nodes 110-130 includes a data drop/add device 125. Node 110 is physically connected to node 120 with a pair of optical fibers 140. Node 120 is physically coupled to node 130 with a further pair of optical fibers 150. FIG. 1 indicates by dashed line segments that additional nodes may be positioned between nodes 120 and 130.
Another instance of a conventional ring network is shown in FIG. 4, where a ring architecture is depicted with three nodes 410, 420, 430 communicatively coupled to a headend. As above, each of the nodes 410-430 includes the data drop/add device 125. However, node 420 is physically connected to node 410 with a single optical fiber 440. Similarly, node 430 is physically coupled to node 420 with a single optical fiber 450. FIG. 4 indicates by dashed line segments that additional nodes may be positioned along fiber 450 between nodes 420 and 430.
A disadvantage of either of the instances shown in FIGS. 1 and 4 is that a break one of the optical fiber lines can prevent all of the nodes from bidirectionally communicating with the headend. Therefore, what is required is solution that provides the network with at least some protection in the event of a break in one of the fiber lines.
One approach to providing some protection in the event of a break in one of the fibers in the past has been to connect the nodes together with redundant parallel fibers. A break in one fiber can then be overcome through the use of a parallel redundant fiber. However, a disadvantage of this approach has been relatively high cost. Therefore, what is also needed is a solution that provides some protection in the event of a fiber break in a more cost-effective manner.
Another problem with this technology has been that expansion of a ring network requires interruption of communication services. Adding a node to the ring requires that the ring be broken, at least temporarily, so that the new node can be inserted into the ring. This break in the ring can prevent all of the nodes from bidirectionally communicating with the headend until the installation is complete. In many commercial settings, such a temporary interruption to install additional nodes is unacceptable. Therefore, what is also required is a solution that permits the network to be expanded without interrupting communication service.
Another problem with this technology has been failure of active equipment along the ring. If one of the data drop/add devices fails, all of the nodes can be prevented from bidirectionally communicating with the headend. Therefore, what is also required is a solution that provides protection in the event of active equipment failure.
Heretofore, the requirement(s) of protection in the event of a line break, expandability without interruption, and protection in the event of active equipment failure, referred to above have not been fully met. What is needed is a solution that addresses at least one, and preferably all, of these requirements. The invention is directed to meeting these requirements, among others.
A goal of the invention is to simultaneously satisfy the above-discussed requirements of network protection in the event of a line break, expandability without communications interruption, and network protection in the event of active equipment failure which, in the case of the prior art, are not satisfied, much less simultaneously satisfied. Another goal of the invention is to satisfying one or two of these requirements.
One embodiment of the invention is based on an apparatus, comprising a communications link, said communications link including a splitter-combiner communicatively coupled to a headend, said splitter-combiner including: a signal splitter communicatively coupled to a headend input and communicatively coupled to a downstream output; and signal combiner communicatively coupled to said signal splitter, communicatively coupled to an upstream input, and communicatively coupled to a headend output. Another embodiment of the invention is based on a method, comprising deploying a communications link at least a portion of which is protected against signal conductor failure, wherein deploying includes providing said communications link with a splitter-combiner that is communicatively coupled to a headend. Another embodiment of the invention is based on a method, comprising deploying a communications link with non-intrusive expansion capability, wherein deploying includes providing said communications link with a splitter-combiner communicatively coupled to a headend.
Another embodiment of the invention is based on an apparatus, comprising a communications link, said communications link including a splitter-combiner communicatively coupled to a headend, said splitter-combiner including: a signal splitter communicatively coupled to a headend input and communicatively coupled to a downstream output; and signal combiner communicatively coupled to said signal splitter, communicatively coupled to an upstream input, and communicatively coupled to a headend output; and a data drop/add device communicatively coupled to said downstream output and communicatively coupled to said upstream input. Another embodiment of the invention is based on an apparatus, comprising a communications link, said communications link including a first splitter-combiner communicatively coupled to a headend, said first splitter-combiner including: a first signal splitter communicatively coupled to a first headend input and communicatively coupled to a first downstream output; and a first signal combiner communicatively coupled to said first signal splitter, communicatively coupled to a first upstream input, and communicatively coupled to a first headend output; a data drop/add device communicatively coupled to said first downstream output and communicatively coupled to said first upstream input; a second splitter-combiner communicatively coupled between said first headend input and said headend, said second splitter-combiner including: a second signal splitter communicatively coupled to said headend and communicatively coupled to a second downstream output; and a second signal combiner communicatively coupled to said second signal splitter, communicatively coupled to a second upstream input, and communicatively coupled to said first headend input. Another embodiment of the invention is based on a method, comprising deploying a communication link, at least a portion of which is protected against active equipment failure, that includes a splitter-combiner communicatively coupled between a data drop/add device and a headend.
These, and other goals and embodiments of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention without departing from the spirit thereof, and the invention includes all such modifications.